Metro networks are often organized in two levels including metro access and metro core systems. Metro access networks are deployed near the end customer while metro core networks aggregate several access networks deployed in different parts of the metro area. The metro core systems also host the gateway(s) to the wide area backbone network. Currently the dominating technology to connect individual customers and businesses to the Internet is a leased 1.5 or 2.0 Mbps TDM circuits from the customer premises to the provider edge node, that is, router or a switch located in the point-of-presence (POP). The edge equipment is populated with channelized TDM interface cards. This TDM circuit, with limited and relatively expensive capacity, is a bottleneck. The access circuit is provisioned separately from the provisioning of the network service, such as an IP service, leading to high operational overhead. When several circuits are aggregated in the TDM access network, statistical sharing of capacity is not possible due to the fixed nature of TDM circuits. Statistical multiplexing of the traffic can occur only first after the traffic reaches the router. The channelized TDM interfaces include complex hardware that monitors each circuit individually but makes line cards expensive.
The capacity bottleneck of the TDM system may be avoided by migrating to a high-capacity packet-based access infrastructure, such as Ethernet. Ethernet equipment is low cost, high capacity, and widely deployed in the industry. Ethernet switches forwards packets based on the destination address. Ethernet switches are intended for friendly enterprise environments and include a number of automatic features in order to ease the installation and operation of the network. However, these automatic features become problematic in large scale operator environments. The automatic features do not scale to large infrastructures and needs sometimes to be disengaged to increase security. This requires manual configuration of possibly a large number of individual units. One specific example of an automatic feature of Ethernet switches is that they dynamically learn each unique source address of the packets received in order to optimize the forwarding of traffic. It is sometimes necessary to disengage this learning process to prevent customers from being able to communicate directly with each other without going through a service provider. In summary, problems with basic Ethernet switches include: no support for customer separation; low degree of security due to the fact that cross traffic directly between end-customers is allowed; dynamic address learning may open up for DoS attacks; and requires distributed element management and service creation due to the fact that a potential large set of distributed units needs to be configured and managed; and the standard based Spanning Tree Protocol (STP) based restoration is slow.
The method of the present invention provides a solution to the above-outlined problems. More particularly, the method is for sending information through a topology. A first and second node each having a first access port, a second access port and a first uplink connected to a first router and a second router, respectively. A third node is provided that has a first access port and a first uplink, the first uplink of the third node being connected to the second access port of the first node. A first packet is sent via the first access port to the third node. The third node adds a first port number to a first section of a tag of the first packet and sends the first packet via the first uplink of the third node to the first access port of the first node. The first node receives the first packet via the first access port of the first node. The first node shifting the first port number to a second section of the tag and adds a first port number of the first access port of the first node to the first section of the tag. The first node sends the first packet via the first uplink of the first node to a first router.